What is that word to describe competitors all clustering in the same location for mutual profit?

You get situations like Harley Street private doctors in London. Some are in the same branch of medicine, yet they all go there because they benefit from the fact that Harley Street is known (or at least believed) to have excellent doctors. They all benefit, even if some customers (patients) choose to go to the building next door.

I know there's a word for this and I think it begins with "f", but that's all I can remember.

Note that I think the word I'm looking for might be quite specifically about being in the same space because competitors are there, e.g. a market is such a thing, because people know if they go to the market they can buy vegetables, some of whom will buy your vegetables and others will buy from your competitors.

In contrast, some businesses end up in the same location for practical reasons, e.g. they need to be near suppliers or other types of business, or there are certain local demographic factors that they rely on. I don't think the word I'm looking for includes those factors; it is specific to deliberately choosing to be near competitors, not, e.g. near your customers or suppliers.

Thanks if you can help find this great word!

Neil

Solution 1:

I think the word you use in the question - clusters - can be used in a strict, academic sense.

Quoting this research paper :
Clusters and Competition. New Agendas for Companies, Governments, and Institutions.
by Michael E. Porter

Clusters are geographic concentrations of interconnected companies, specialized suppliers, service providers, firms in related industries, and associated institutions (for example, universities, standards agencies, and trade associations) in particular fields that compete but also cooperate. Critical masses of unusual competitive success in particular business areas, clusters are a striking feature of virtually every national, regional, state, and even metropoli- tan economy, especially those of more economi- cally advanced nations.

[...]

The health of the cluster is important to the health of the company. A company may actually benefit from the presence of local competitors.

[...]